There is leeway for players to carry out a limited degree of role-play outside the formal game mechanics without the consent of other players; read section 21 in full for more information on that. There is also a specific procedure available to role-play significant events - even wars - without the consent of a minority of players involved; see section 23 to learn more about that. However, the co-operation and consent of players should always be aimed for. As section 21 begins, "Role-play is most enjoyable and successful when there is good communication and friendly relations between all players involved", and as it actually requires,
21.4 Players are expected to behave in a courteous, co-operative manner and make a reasonable effort to act with the consent of all players involved, even where the rules do not make consent strictly necessary. In particular, players have a responsibility to take reasonable care that other players are not misinformed either about the role-play or the Game Rules.
There are situations in-game where the preferences of players are not solicited at all, or if they are expressed, are blatantly over-ridden. Sometimes players feel steamrollered into things they are not really comfortable with. They may be reluctant to challenge a player who seems dominant and determined, and sometimes they might not be sure about what the rules are or whether anything can be done. There have been cases where players have actually been misled by other players about what the rules actually are. This is all obviously unfortunate, and over time it can end up doing some degree of harm to the general experience players have of the game.
So the message I want to get out is: if you're feeling pressured into accepting role-play you're not comfortable with, stay courteous but please clearly register your objection and do not let them push you around! Familiarise yourself with the Game Rules, especially the sections on role-play (section 21 onwards). And if a situation is becoming troublesome, or you just want clarity about something (however minor), please do not hesitate to come to me. I'm friendly, I'm here to help and I won't bite your head off (honest!).